Engine manufacturers strive to improve performance of internal combustion engines by maximizing the conversion of chemical energy to mechanical energy. The conversion efficiency may be improved when losses of energy used to overcome friction between moving parts in the engine are reduced. Mechanical design along with oil and other lubricants aid in reducing these losses.
Roller follower assemblies are mechanical design improvements that reduce friction losses between a cam and a rocker arm. Past systems used a sliding contact between the cam and rocker arm. These systems resulted in large frictional losses. Also, these systems experienced increased wear. Roller follower assemblies reduce friction between the cam and rocker arm by changing the sliding contact to a rolling contact. However, roller follower assemblies may still have a problem with wear.
Each roller rotates about an axle pin. Typically, oil reduces sliding friction between a roller and an axle pin. Oil also provides an additional and equally important role of cleaning the engine. Oil along with an oil filter system may remove particles above a particular size. However, the roller and axle pin may ingest smaller particles. At some point these small particles may cause sliding between the roller and axle pin to cease. The interruption in sliding stops the rolling contact between the cam and roller and causes sliding contact between the cam and roller. The sliding contact between the roller and cam may cause a tearing damage at their respective surfaces.
The present invention is directed to overcoming one or more of the problems set forth above.